A review of the technology available for the control of atmospheric emissions from oil sands plants

Dynawest Projects Ltd. has been commissioned by Alberta Environment to provide an overview of the technology available for the control of sulphur and nitrogen oxide emissions from oil sands plants. The study scope is summarized below: 1. Review briefly bitumen extraction and upgrading technologies. 2. Review and update Claus sulphur recovery technologies. 3. Review and update tail gas clean-up technologies. 4. Review and update flue gas desulphurization technologies. 5. Review air fluidized bed technologies. 6. Review coke gasification technologies. 7. Review control systems for oxides of nitrogen. The content of the main sections of the report is summarized below. All economic data is presented in mid 1982 Canadian dollars and refers to process units whose capacity is based on the oil sands upgrading configuration shown in Figure 1. 1. Claus Plant Technology The Claus process for the recovery of sulphur from gas streams containing hydrogen sulphide is well proven and used throughout the world. Both existing oil sands plants incorporate the process. Different acid gas compositions require alternative process configurations for successful treatment. Acid gas composition and operating procedures are the principal determinants of catalyst deactivation rates. The capital and annual operating costs of the process are shown on Table II. 2. Tail Gas Treatment Processes Several processes for the recovery of sulphur from Claus plant tail gas are available; none has yet been installed at an oil sands plant. Processes described are listed in Table III which shows the state of development of each, and identifies which processes increase the capacity of the parent Claus plant by recycling material to it. The capital and annual operating costs of the processes described are shown on Table IV. 3. Flue Gas Desulphurization Processes A number of processes for the removal of SO2 from flue gas are available; none has yet been installed at an oil sands plant. Processes described are listed in Table V which shows the state of development of each, identifies principal reagents, byproducts and upper limit (if any) on the SO2 content of the flue gas to be treated. The capital and annual operating costs of the processes described are shown on Table VI. 4. Residue Gasification Several processes, most of which were originally developed for the gasification of coal, are available. Table VII summarizes the salient features of those described in the report. Consideration of the potential application of residue gasification in an oil sands plant suggests that an entrained flow gasifier would be more appropriate than either a fixed or fluidized bed. Operating and design considerations for entrained flow gasifiers are described in some detail. The most probable use of residue gasification in an oil sands complex is for the production of hydrogen. The capital and annual operating costs of a fully integrated hydrogen production plant based on residue gasification are shown on Table VIII. 5. Fluidized Bed Combustion Fluidized Bed Combustion combines combustion, heat transfer and desulphurization in a single operation. The technology shows a cost advantage over conventional pulverized fuel combustion only when flue gas desulphurization would otherwise be required. Most major processes are still at the development stage with only small industrial units (up to 75 t/h of steam) being offered commercially. 6. NOx Emission Control Fuel combustion is the principal source of NOx emissions from an oil sands complex. Three strategies are available for emission control: operational modifications; equipment design and modification; and NOx removal. The latter is the most effective and expensive. The technology is well established and its application to oil sands plants presents no special problems. The Alberta Government has established guidelines limiting the total emission of sulphur from an oil sands operation to 3.2 t per 1000 m3 of bitumen fed to the upgrading process (0.5 long tons per 1000 bbl). The incremental cost of attaining this standard by progressively increasing expenditure on pollution control equipment is summarized on Figure II which demonstrates the application of the law of diminishing returns as additional technology is added to the basic Claus plant.

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